The overexpression of the protein was particularly evident in SKBR3 cells, a human breast cancer cell line that overexpresses the HER2 (Neu/ErbB-2) gene product, where its silencing reduced cell proliferation associated with a block of cell cycle progression in the G2/M phase due to the upregulation of p27, a cell-cycle inhibitor [33]. This evidence concerns the gene ERBB2 and breast cancer.